1. Field of Invention
This invention relates to decorating extruded plastic slat material for use in vertical or horizontal blinds, and, more particularly, to simultaneously applying an embossed relief pattern and an ink printed pattern to such material following its discharge from an extrusion die, with the printed pattern and the embossed relief pattern having a predetermined relationship with one another.
2. Description of the Related Art
A number of patents describe methods for applying an embossed texture pattern to extruded plastic slat material for vertical blinds. For example, U.S. Pat. No. 5,311,514 describes an assembly for forming or embossing a decorative pattern on at least one exposed surface of an elongated slat, particularly of the type used in a vertical blind assembly. A pair of driven rollers engage opposite sides of a slat immediately after its formation by a plastic extruder. The exterior surfaces of one of the rollers has decorative patterns formed therein. The temperatures of the rollers are regulated to facilitate transfer of the decorative pattern, continuous movement of the slat through the rollers, and formation of the transverse or cross-sectional configuration of the slat concurrently to placing the decorative pattern thereon. While such patents describe means for placing a texture pattern on the slat, what is needed is a method for also applying a printed pattern, disposed in a preferred pattern related to the texture pattern, on the slat material.
A number of other patents describe various methods for providing slat material having color patterns and texture patterns in registration with one another. For example, U.S. Pat. No. 4,842,036 describes vertical blind slat assemblies including laminates comprising strand material which is not free hanging and in which there are substantial spaces between strands to allow light to pass through the material, and a sheet-like layer to which the strand material is secured, so that the strands of the laminate are fixed. The laminates allow the color or other characteristics of a slat member or insert to be seen. The laminates can have differing surface characteristics (e.g. texture) and strand colors, sizes, and patterns. The laminate can be attached to the slat member directly, as by adhesive, or it may removably secured to a groover slat member. While the desirability of a pattern of raised or textured surfaces, with a corresponding color pattern, is thus recognized, what is needed is a method for forming a slat having such patterns in an integral part, without requiring assembly procedures.
U.S. Pat. No. 4,116,737 describes a method for creating an embossed effect in a desired pattern on a film by printing an agent on the film in the desired pattern to lower the stability of the film in the print areas against heat distortion and laminating the film to a substrate by fusion immediately after the substrate is extruded to cause the print areas to distort and give an embossed appearance as a result of the heat incident to the fusion. While this method is adapted for simulating the texture of a wood grain pattern, what is needed is a method to form relatively large texture objects providing greater flexibility in the design of the texture pattern, and a method for forming an integral part without a need for laminating separate materials.
U.S. Pat. No. 4,223,057 describes a fabric containing thermoplastic fibers, which is simultaneously printed with a first pattern in a sublimable or vaporizable dye and embossed or surface textured with a second pattern, without substantial effect on the printing of the first pattern, by the application of heat and pressure to a stack comprising a heat transfer printing sheet bearing a vaporizable or sublimable dye in the first pattern, an embossing sheet of material permeable to said dye and having no affinity or retention properties therefor, and having a second pattern formed in relief in at least one surface thereof, and a sheet of fabric to be printed and embossed. The printing and embossing sheets may be combined into a unitary sheet, and the embossing sheet may include a dye trap such as an emulsion or solution of an acrylic resin disposed in a third pattern. This process relates to the simultaneous heat transfer printing and embossing or surface texturing of fabrics and other sheet materials. What is needed is a method for using an embossing medium to carry inks for printing a desired pattern of color without requiring the use of a separate transfer sheet and without placing a requirement on the embossing material to allow transmission therethrough of a dye material. Also, what is needed is a method for simultaneously printing and embossing relatively thick and non-fiberous materials, such as slats for vertical blinds.
U.S. Pat. No. 6,006,816 describes a method in which extruded material for forming blind slats, and having at least one textured surface with raised areas and adjacent lower areas, is passed through a spray painting process applying a substantially thicker coating of paint to the raised areas than to the adjacent lower areas. While this method applies a colored paint image to slat material after it has been embossed, what is needed is a method having more control over the painted image, which also allows greater variations in parameters affecting the painted image, and a method simultaneously applying the embossed and printed image, which can be accomplished without the using a dedicated paint spray.
A number of other patents describe methods for applying ink to operating surfaces within printing apparatus. For example, U.S. Pat. No. 4,936,215 describes printing apparatus including a printing roller which abuts the cylindrical surface of an impression roller, in which ink is transferred from an anilox roller via the printing roller to the impression roller. What is needed is apparatus incorporating both a printing function and an embossing function for application to extruded slat material.
In accordance with a first aspect of the present invention, a method, including steps of applying ink to a peripheral surface of an embossing roller and bringing the peripheral surface of the embossing roller into rolling contact with a surface of thermoplastic slat material, is provided for applying a decorative relief pattern to the surface of the slat material. The embossing roller includes an inverse relief pattern, which is an inverse of the decorative relief pattern. That is, the inverse relief pattern has grooves to form ridges in the decorative relief pattern, etc. The ink forms an ink layer extending along a portion of the peripheral surface of the embossing roller and varying in thickness in accordance to features of the inverse relief pattern. The inverse pattern forms the decorative relief pattern on the surface of the slat material, with a portion of the ink layer being transferred from the peripheral surface of the embossing roller to the surface of the slat material.
The inverse relief pattern preferably includes areas at various levels of depression from an outer surface level of the inverse relief pattern. The ink layer is applied to the peripheral surface of the embossing roller from a transfer surface having an ink coating with a predetermined thickness, with the ink layer on the peripheral surface of the embossing roller decreasing in thickness with increases in levels of depression from the outer surface level.
The inverse relief pattern preferably also includes areas having various textures, including smooth and rough areas, with the method additionally including a step of exposing the peripheral surface of the embossing roller to a stream of air directed at the peripheral surface between the steps of applying ink to the peripheral surface and of bringing the peripheral surface into rolling contact with a surface of the slat material. This stream of air removes ink preferentially from smooth areas, while ink is retained in the rough areas.
This method may be applied only to a first side of the slat material, with the reverse side of the slat material remaining smooth, or the method may be applied to the second side of the slat material following its application to the first side, so that both sides are textured and colored with an ink pattern.